1. Field of the Invention
This invention relates to the field of radiation physics. More particularly, this invention relates to signal search, acquisition, and tracking systems. Still more particularly, the invention relates to an electronically scanned array used in such a tracking system. By way of further characterization the invention will be described as it relates to an electrically scanned array whose scan is controlled by a microprocessor which also controls the receiver tuning and the simultaneous angle tracking and frequency tracking of a received signal.
2. Description of the Prior Art
Bicone antennas and their radiation pattern when stacked in a collinear array are well known as is electronic scanning of an array pattern by phase shifting. Search and tracking systems using gimbel mounted antenna systems having helical, raster, or nodding scans have been utilized in the past. In shipboard application such antennas require complex and costly inertial stabilization inputs to accurately present information on elevated targets due to pitch and roll of the ship. Further the scan period to cover an entire hemisphere is limited by physical constraints on antenna rotation, tilt, and beam width in such systems.